ZnO is an N-type semiconductor material with a large band gap (3.37eV) and a high exciton binding energy (60 meV), high electron mobility and thermal conductivity. At the same time, it also has the ability to prepare It has the advantages of low cost, non-toxicity, light weight, and degradability. As a functional material, it has broad application prospects. It has a wide range of applications in the fields of gas sensitivity, luminescence, catalysis, etc. At the same time, zinc oxide has a large dielectric constant in the electromagnetic field. Excellent dielectric loss and semiconductor performance, it is an excellent wave absorbing material.
The microwave absorption performance is often related to the material's complex permeability, complex permittivity, and impedance matching. These parameters can be adjusted by the material's composition, morphology, size, etc.
Studies have found that some ZnO with special morphology tends to show better absorbing properties
Doping with transition metal ions in ZnO, or compounding with carbon-based absorbing materials can introduce the excellent performance of other absorbing materials.

Above are theories from researchers for your reference only, detailed application would needs your testing, thanks.